Math Problem Statement

Find the minimum and maximum values of $f(x) = \frac{x^2 + 1}{x}$ on $[-2,0)$.

Solution

We are tasked with finding the minimum and maximum values of the function f(x)=x2+1xf(x) = \frac{x^2 + 1}{x} on the interval [2,0)[-2, 0).

Step 1: Rewrite the Function

First, simplify f(x)f(x):

f(x)=x2+1x=x+1xf(x) = \frac{x^2 + 1}{x} = x + \frac{1}{x}

Step 2: Compute the Derivative

To find the critical points, we first need to compute the derivative of f(x)f(x).

f(x)=ddx(x+1x)=11x2f'(x) = \frac{d}{dx}\left( x + \frac{1}{x} \right) = 1 - \frac{1}{x^2}

Step 3: Solve for Critical Points

Set f(x)=0f'(x) = 0 to find the critical points:

11x2=01 - \frac{1}{x^2} = 0

1x2=1x2=1x=±1\frac{1}{x^2} = 1 \quad \Rightarrow \quad x^2 = 1 \quad \Rightarrow \quad x = \pm 1

However, since xx is restricted to the interval [2,0)[-2, 0), only x=1x = -1 is valid.

Step 4: Evaluate the Function at Critical Points and Endpoints

Now, evaluate f(x)f(x) at the critical point and at the endpoints of the interval.

  • At x=1x = -1:

f(1)=1+11=11=2f(-1) = -1 + \frac{1}{-1} = -1 - 1 = -2

  • At x=2x = -2:

f(2)=2+12=212=52f(-2) = -2 + \frac{1}{-2} = -2 - \frac{1}{2} = -\frac{5}{2}

  • At x0x \to 0^- (as xx approaches 0 from the left):

f(x)=x+1xapproachesf(x) = x + \frac{1}{x} \quad \text{approaches} \quad -\infty as 1x\frac{1}{x} tends to -\infty.

Step 5: Determine Minimum and Maximum Values

From the evaluations:

  • The maximum value is f(1)=2f(-1) = -2.
  • The function decreases without bound as x0x \to 0^-, so the minimum value does not exist (the function tends to -\infty).

Conclusion:

  • The maximum value of f(x)f(x) on [2,0)[-2, 0) is 2-2.
  • The function has no minimum value as it tends to -\infty as x0x \to 0^-.

Would you like further details on this solution?


Here are 5 related questions:

  1. How would the problem change if the interval included 0?
  2. What is the behavior of f(x)f(x) on a different interval, such as (,0)(-\infty, 0)?
  3. Can you explain the role of critical points in determining extremum values?
  4. What are the conditions for a function to have absolute extrema?
  5. How does asymptotic behavior influence the analysis of functions near boundary points?

Tip: Always analyze the behavior of functions near the boundaries when dealing with open intervals to understand how the function behaves as it approaches those points.

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Math Problem Analysis

Mathematical Concepts

Calculus
Optimization
Critical Points
Limits
Behavior of Functions on Intervals

Formulas

Derivative of f(x): f'(x) = 1 - \frac{1}{x^2}
Function simplification: f(x) = x + \frac{1}{x}

Theorems

Critical Points Theorem
Limits and Asymptotic Behavior

Suitable Grade Level

Grades 11-12 or early college